Clumping animal litters are typically provided in the form of discrete plural particles. The particles tend to agglomerate into solid masses or clumps when wetted by a liquid waste such as animal urine. A number of such clumping litters are known. One advantage of such clumping litters is that the solid clumps, which are formed upon wetting of the litter, can be separately removed as discrete entities from the remaining litter. The clumped litter can be discarded by the animal owner, leaving behind a quantity of relatively uncontaminated litter for future use. Animal owners, particularly owners of house cats, often find the clumping property of such litters to be convenient for periodic cleaning of the animal litter box. Ammonia-masking properties also are desirable in animal litters because ammonia, a breakdown product of the urea found in animal urine, is a significant factor that contributes to the undesirable odor of animal waste. Some known animal litters have good ammonia-masking properties.
Many clumping animal litters are made from clays and other mineral substrates. Such litters typically include particles of a mineral substrate, which substrate functions as an absorbent and/or odor reducer. The particles may be coated with a liquid-activated adhesive material, such as gelatinized starch, on the surfaces of the particles. When wetted, the adhesive material is activated and causes the discrete litter particles to agglomerate into clumps.
Although clay-based litters may be functional as clumping animal litters, such litters suffer from certain drawbacks. For example, one disadvantage of clay litters is the high density of the clay component of the litter. Because of this high density, a relatively heavy mass of litter must be used for a given volume of urine. In addition, the resulting clumps of soiled litter are somewhat heavy, and thus can fracture in the absence of strong interparticle adhesion. Another disadvantage of clay litters is that, because the clay is not biodegradable, the litter cannot be flushed into some sewage systems after use. This may be inconvenient for certain animal owners.
In recognition of these drawbacks, animal litters made from biodegradable materials, such as seed hulls or other grain-based materials, have been provided. Such litters are often suitable for disposal by flushing into sewage systems. For instance, U.S. Pat. No. 6,014,947 purports to disclose a grain-based litter made from whole wheat or other ground grains. In recognition of the advantages inherent in clumping animal litters, biodegradable litters that exhibit a clumping property have undergone development. Like typical clumping clay litters, such litters often comprise discrete particles of a liquid-absorbent substrate having a liquid-activated adhesive coated thereon.
Many known grain-based litters, however, also suffer from drawbacks. For example, soiled clumps of such grain-based litters typically are more friable than clumps of clay-based litters. Moreover, while grain-based clumping litters may initially form cohesive clumps, the long-term cohesiveness of the formed clumps may be poor. Thus, while a solid clump may be formed and remain solid for a short period of time, the clump may tend to disintegrate with time or on handling, making it difficult to separate the soiled clumped litter from the unspoiled litter.
Another problem with both clay-based and grain-based clumping litters relates to clumping efficiency, or the amount of litter required to form a clump. Large amounts of conventional litters are required to form a clump, and thus conventional clumping litters are used up quickly. The animal owner thus is forced to replenish the supply of litter frequently.
Numerous litters and sorbents have been provided in the art, and many of these are based on citrus products. U.S. Pat. Nos. 4,386,580; 4,424,263; and 4,446,019, for instance, disclose the use of dry citrus pulps in an animal litter. U.S. Pat. Nos. 4,737,582 and 4,883,021 purportedly disclose pectin-containing absorbent materials. Other patents that purport to describe asborbents based on citrus products include U.S. Pat. Nos. 5,188,064 and 5,361,219. Another reference, U.S. Pat. No. 4,222,824, discloses cyclodextrin and cellulose in animal litter. For various reasons, the products purportedly disclosed in the foregoing patents are believed to be unsatisfactory.
In light of the drawbacks inherent in known clay-based and grain-based animal litters, there exists a need for a more satisfactory biodegradable clumpable animal litter. Ideally, the litter should be made from a renewable, biodegradable resource, such as a grain-based substrate. The litter also should possess acceptable clumping properties, such as low clump mass, initial cohesiveness of the clumps, and long-term cohesiveness of the clumps.
Grain-based litters with improved clumping properties have been developed and such litters are taught in U.S. Pat. Nos. 6,089,569 and 6,216,634 (both to Kent et al., assignors to Grain Processing Corporation of Muscatine, Iowa). These litters have many excellent properties. It is a general object of this invention to provide additional animal litters that are formulated with grains and other biodegradable materials.